An active phased-array design for electronic two-dimensional beam scanning using a phase-shifterless linear one-dimensional active leaky-wave antenna array is demonstrated. The varactor-tuned voltage-controlled oscillators (VCOs) and coupling network are implemented in this array. Three coupling networks are designed and compared for optimum coupling strength between each VCO element. The measured pattern of a 4/spl times/1 active leaky-wave antenna array shows that the main beam can be continuously scanned from 68/spl deg/ to 40/spl deg/ in elevation, as the frequency varies from 8.24 GHz to 9.15 GHz. This is equivalent to over 10% electronic tuning bandwidth. By tuning the free-running frequencies of the end elements, the main beam can be continuously scanned from -26/spl deg/ to +10/spl deg/ from broadside with azimuth symmetry in a conical scan manner.
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